Turbine engine cleaning



United. States Patent 3,400,017 TURBINE ENGINE CLEANING George J. Huebuer, Jr., Bloomfield Hills, and Dwight Maxwell Teague, Detroit, Mich., assiguors to Chrysler Corporation, Highland Park, Mich., a corporation of Delaware No Drawing. Continuation of application Ser. No.

459,121, May 26, 1965. This application Mar. 21,

1967, Ser. No. 624,966

7 Claims. (Cl. 1 34--7) This is a continuation application of application Ser. No. 459,121, filed May 26, 1965, now abandoned.

This invention relates to a method for cleaning gas turbine engines. More particularly, this invention relates to a method for cleaning certain internal components of a turbine engine without the need of removing the components from the engine. The method of this invention finds special application in the cleaning of the air compressor section of a regenerative gas turbine engine.

Increasing efforts are being made toward the development of gas turbine engines. Such engines are used in the aircraft industry, and, an increasing number of experimental engines are being used in trucks and passenger cars. However, with the accelerating use of such engines, a problem has come into focus with respect to the maintenance of their proper operating efiiciency. This problem stems from the fact that certain of the turbine engine components are quite susceptible to becoming coated with road dirt and oil film. Furthermore, it has been found that the formation of dirt deposits on components, such as diffuser passages and turbine wheel and air compressor blades, substantially reduces the efficiency and power output of the engine. Furthermore, it has been established that such reduced operating performance is primarily caused by accumulation of dirt on the engine air compressor. Accordingly, in order to solve this problem, rather sophisticated air filters have been designed and installed in the air intake system of the engine. However, this approach has not solved the problem, even though such filters are effective in preventing dirt particles as small as five microns from entering the engine. Since the use of still more effective filters is prohibited because they interfere with the required air flow which is so necessary to proper engine performance, it has become necessary to clean the engine components. Furthermore, depending on the conditions of engine use, such cleanings are needed at frequent intervals. Because the components which need cleaning are inside the engine housing, it was heretofore thought to be necessary that the engine be disassembled in order to manually clean them. Naturally, such a procedure is undesirable due to the time and cost involved. Accordingly, the problem of how to provide the necessary cleaning is a serious obstacle in the large scale use of gas turbine engines. In order to overcome this problem, many cleaning methods have been tried such as injecting detergents, soaps, degreasing fluids or water into the engine. However, this approach failed since liquids seem to lack sufiicient scrubbing action. Another method used involved injecting a solid material into the engine such as ground pecan shells or corn cobs. Again, the use of such materials did not solve the problem since they damaged the compressor blade surfaces and seals. Furthermore, the use of such materials is prohibited in regenerative gas turbine engines wherein regenerators are employed since the materials become lodged in the regenerator core and seals.

Accordingly, an object of this invention is to provide a method of cleaning certain internal components of axial or radial compressor type gas turbine engines.

A further object is to provide a method of cleaning in 'ice which the components of the engine which need to be cleaned do not have to be removed from the engine.

Yet another object is to provide a cleaning method which is simple and economical to perform and which is highly effective in cleaning the air compressor and diffuser area of a regenerative gas turbine engine.

Other objects and advantages of this invention will become apparent from the following detailed description.

The method of this invention comprises the steps of introducing solid particles of a material into the air intake system of the engine, passing the solid particles through a portion of the engine wherein they will gain velocity, impinging the particles on the component to be cleaned and then vaporizing the particles and removing the vapor from the engine.

The cleaning action in the method of this invention is apparently caused by the abrasion action of the particles on the surface to be cleaned. Furthermore, the method is highly effective since the particles are forced into the components in exactly the same manner as are dirt particles. Therefore, the abrasive action occurs in the same location where the dirt particles have accumulated. In order to achieve good cleaning action it is necessary that the particles have sufiicient momentum when they strike so as to remove the dirt deposits and yet not damage the components. It has been found that particles having diameters in the range of about 1 mil to mils provide the most satisfactory cleaning action. Final particle size selection will depend primarily on the hardness and volatility of the particle material. The preferred particle size of the solid is from about 5 to 50 mils.

In the method of this invention, it is necessary that the cleaning material be readily vaporized so that it can quickly be expelled from the engine without damaging any of the seals or other intricate parts thereof. This vaporization requirement is especially important with respect to regenerative gas turbine engines. In this type of engine, the air entering the engine passes through the air compressor section and then into the regenerator which is a component having many small passages, much like an automobile radiator, and an elaborate system of seals. Accordingly, while the cleaning material must initially be in solid form so as to provide abrasive cleaning action, it must also be capable of being vaporized so that it may pass through the regenerator without damaging it. It will be understood that a material can be used which will liquefy and then be vaporized. However, a material which sublimes, that is, passes directly from the solid to the vapor state is preferred. In any event, whether the material sublimes or first passes through the liquid state, it must vaporize, under essentially atmospheric pressure, at a temperature not in excess of 400 F., that is, a temperature of 400 F. or less. A preferable material is one that will vaporize at a temperature in the range of about 100 F. to 275 F. Naturally, a further requirement for the cleaning material is that it leaves no carbonaceous residue or ash which would itself hinder engine performance.

Compounds which meet the above requirements and are suitable for use in this invention include ammonium carbonate, ammonium bicarbonate, ammonium chloride, naphthalene, camphor, and mixtures of the foregoing. The preferred materials for use in the method of this invention are ammonium carbonate and ammonium bicarbonate.

The method of this invention has been used to clean many regenerative gas turbine engines having radial air compressors which were mounted in automobiles. In the cleaning procedure, the turbine engine was started and the engine was allowed to idle thereby operating the air compressor at about 20,000 rpm. The air intake filter was removed and dry ammonium carbonate powder was poured into the air intake whereupon it was sucked into the air compressor and diffuser area of the engine. The quantity of cleaning agent used is not critical and will vary depending on the condition of the engine. In general, it has been found that between one and two pints of ammonium carbonate are sufilcient. Again, the rate of addition of the cleaning agent to the engine is not critical and excellent results have been obtained when two pints of ammonium carbonate are introduced over a period of about one minute. After the ammonium carbonate was added, the engine was allowed to continue idling for a period of about fifteen minutes so as to allow the carbonate to vaporize and be expelled from the engine via the exhaust system.

The results obtained from cleaning a gas turbine engine by the method of this invention are quite amazing. For example, an automobile powered by a gas turbine engine had an acceleration from to 60 miles per hour of seconds. With no other work being done on the vehicle other than cleaning the engine in accordance with the procedure set forth above, this acceleration time was reduced to 11 seconds. Likewise, an engine which was rated at 108 horsepower before cleaning, measured 138 horsepower after cleaning.

It will be apparent from the foregoing description that the objects of this invention have been obtained. A method for cleaning the internal components of a gas turbine engine has been provided which will not result in damage to the engine and, yet, is convenient, economical and highly efiective.

What is claimed is:

1. A method for cleaning the internal components of a turbine engine which comprises the steps of cranking the engine until it becomes self-sustaining, forming a mixture of air and solid abrasive by introducing solid particles of an abrasive into the engine air intake system, said abrasive being selected from the group consisting of ammonium carbonate, ammonium bicarbonate, ammonium chloride, naphthalene, camphor and mixtures of the foregoing, propelling said mixture by means of said engine through a portion of said engine and impinging the abrasive on the internal components of that portion, increasing the temperature of said mixture as it passes through said engine portion by maintaining said engine in a selfsustaining condition, and controlling the particle size of the abrasive introduced into said air intake so that the abrasive is vaporized in said engine after impinging upon said engine portion.

2. The method of claim 1 wherein the abrasive is ammonium carbonate.

3. A method for cleaning the internal components of a regenerative gas turbine engine which comprises the steps of cranking the engine until it becomes self-sustaining, forming a mixture of air and solid abrasive by introducing solid particles of an abrasive into the engine air intake system, said abrasive being selected from the group consisting of ammonium carbonate, ammonium bicarbonate, ammonium chloride, naphthalene, camphor and mixtures of the foregoing, propelling said mixture by means of said engine through a portion of said engine and impinging the abrasive on the internal components of that portion, increasing the temperature of said mixture as it passes through said engine portion by maintaining said engine in a self-sustaining condition, and controlling the particle size of the abrasive introduced into said air intake so that the abrasive is vaporized before it is impinged upon said regenerator.

4. The method of claim 3 wherein said abrasive has a particle diameter size in the range of about 1 to 100 mils.

5. The method of claim 3 wherein the material is ammonium carbonate.

6. The method of claim 3 wherein the material is ammonium bicarbonate.

7. The method of claim 6 wherein the ammonium bicarbonate has a particle size diameter in the range of about 5 to mils.

References Cited UNITED STATES PATENTS 2,698,265 12/1954 Klingel 134-8 2,701,220 2/1955 Smith 134-7 3,074,822 1/1963 Walker et a1. 134-7 FOREIGN PATENTS 810,889 3/1959 Great Britain.

MORRIS o. WOLK, Primary Examiner.

I. T. ZATARGA, Assistant Examiner. 

1. A METHOD FOR CLEANING THE INTERNAL COMPONENTS OF A TURBING ENGINE WHICH COMPRISES THE STEPS OF CRANKING THE ENGINE UNTIL IT BECOMES SELF-SUSTAINING, FORMING A MIXTURE OF AIR AND SOLID ABRASIVE BY INTRODUCING SOLID PARTICLES OF AN ABRASIVE INTO THE ENGINE AIR INTAKE SYSTEM, SAID ABRASIVE BEING SELECTED FROM THE GROUP CONSISTING OF AMMONIUM CARBONATE, AMMONIUM BICARBONATE, AMMONIUM CHLORIDE, NAPTHALENE, CAMPHOR AND MIXTURES OF THE FOREGOING, PROPELLING SAID MIXTURE BY MEANS OF SAID ENGINE THROUGH A PORTION OF SAID ENGINE AND IMPINGING THE ABRASIVE ON THE INTERNAL COMPONENTS OF THAT PORTION, INCREASING THE TEMPERATURE OF SAID MIXTURE AS IT PASSES THROUGH SAID ENGINE PORTION BY MAINTAINING SAID ENGINE IN A SELFSUSTAINING CONDITION, AND CONTROLLING THE PARTICLE SIZE OF THE ABRASIVE INTRODUCED INTO SAID AIR INTAKE SO THAT THE ABRASIVE IS VAPORIZED IN SAID ENGINE AFTER IMPINGING UPON AID ENGINE PORTION. 